This research focuses on the macromolecular organization of the connective tissue as it relates to defining the pathways by which its major structural component, collagen, is degraded and removed. A detailed understanding of the mode of action of human and animal collagenases, their control, and the cell types responsible for their biosynthesis, is essential in gaining further insight into the process of collagen remodeling. It is our particular aim to relate the information obtained to human diseases in which alterations in the connective tissue occur. BIBLIOGRAPHIC REFERENCES: Davis, B.P., Jeffrey, J.J., Eisen, A.Z. and Derby, A. (1975). The induction of collagenase by thyroxine in resorbing tadpole tailfin in vitro. Develop. Biol., 44, 217-222. Bauer, E.A., Stricklin, G.S., Jeffrey, J.J. and Eisen, A.Z. (1975). Collagenase production by human skin fibroblasts. Biochem. Biophys. Res. Comm. 64, 232-240.